1A6L

T14C MUTANT OF AZOTOBACTER VINELANDII FDI

Summary for 1A6L

• Entry DOI: 10.2210/pdb1a6l/pdb
• Descriptor: FERREDOXIN, IRON/SULFUR CLUSTER, FE3-S4 CLUSTER, ... (4 entities in total)
• Functional Keywords: electron transport, iron-sulfur
• Biological source: Azotobacter vinelandii
• Total number of polymer chains: 1
• Total formula weight: 12709.00

Authors

Gao-Sheridan, H.S.,Kemper, M.A.,Khayat, R.,Armstrong, F.A.,Prasad, G.S.,Sridhar, V.,Stout, C.D.,Burgess, B.K. (deposition date: 1998-02-26, release date: 1998-05-27, Last modification date: 2024-05-22)

Primary citation

Gao-Sheridan, H.S.,Kemper, M.A.,Khayat, R.,Tilley, G.J.,Armstrong, F.A.,Sridhar, V.,Prasad, G.S.,Stout, C.D.,Burgess, B.K.
A T14C variant of Azotobacter vinelandii ferredoxin I undergoes facile [3Fe-4S]0 to [4Fe-4S]2+ conversion in vitro but not in vivo.
J.Biol.Chem., 273:33692-33701, 1998

PubMed Abstract: [4Fe-4S]2+/+ clusters that are ligated by Cys-X-X-Cys-X-X-Cys sequence motifs share the general feature of being hard to convert to [3Fe-4S]+/0 clusters, whereas those that contain a Cys-X-X-Asp-X-X-Cys motif undergo facile and reversible cluster interconversion. Little is known about the factors that control the in vivo assembly and conversion of these clusters. In this study we have designed and constructed a 3Fe to 4Fe cluster conversion variant of Azotobacter vinelandii ferredoxin I (FdI) in which the sequence that ligates the [3Fe-4S] cluster in native FdI was altered by converting a nearby residue, Thr-14, to Cys. Spectroscopic and electrochemical characterization shows that when purified in the presence of dithionite, T14C FdI is an O2-sensitive 8Fe protein. Both the new and the indigenous clusters have reduction potentials that are significantly shifted compared with those in native FdI, strongly suggesting a significantly altered environment around the clusters. Interestingly, whole cell EPR have revealed that T14C FdI exists as a 7Fe protein in vivo. This 7Fe form of T14C FdI is extremely similar to native FdI in its spectroscopic, electrochemical, and structural features. However, unlike native FdI which does not undergo facile cluster conversion, the 7Fe form T14C FdI quickly converts to the 8Fe form with a high efficiency under reducing conditions.

PubMed: 9837955
DOI: 10.1074/jbc.273.50.33692

Experimental method

X-RAY DIFFRACTION (2.1 Å)